We all know that there is so much water locked up in the ice of Greenland and Antarctica that if it melted it will cause serious flooding. In all the large figures of sea level rise it should be remembered that just one metre rise will bring massive economic losses for every country with a shoreline. There are two big ice sheet regions, Antarctica and Greenland. Antarctica is split in two with East and West and we can ignore East Antarctica which is so high and cold it is not melting yet. This leaves West Antarctica which has enough ice to raise sea levels 4.8 meters and Greenland which has enough ice to raise 7.5 meters, they are both completely different and both of them have melted completely in the distant past.

﻿﻿Greenland is a high rocky island which has ice on its surface that is two kilometres thick and has glacier tails that sit in the sea, Its vulnerability is that its surface melts in the summer and when it does so the dark blue water absorbs more of the sun’s heat than white ice and this warmer water melts into the ice and eventually makes a hole that will carry a whole lake of warm water into its interior.﻿

Not much is known about where this warm water goes but the concern here is that the increasing number of holes in the ice and the amount of warm water in the interior are weakening the ice sheets core which will become rotten and vulnerable to catastrophic collapse. There are many elements to Greenland’s ill health, including the amount of soot on the surface that speeds melt and also the increasing speed of glaciers heading to the sea. All in all Greenland is not in good shape.

West Antarctica has a different set of problems in that it is a string of islands that are covered in a huge sheet of ice but much of this ice is sitting on the sea bed. The concern here is that the sea water is warming and washing around the bottom of the ice and melting it rapidly. Water has a thermal conductivity that is 24 times greater than air so it has a greater capacity to melt ice quickly and the ocean water is warming.

Two East Antarctica ice sheets have broken off and collapsed already but these were floating in the sea and did not add much to sea level rise but they did demonstrate the vulnerability of West Antarctica. The warmer water has been measured at melting 50 mm of ice a day which may not seem much if the ice is 1000 metres thick but it weakens the sheet and then storm waves can break the sheet which then collapses. The problem in forecasting a sudden collapse is working out the mechanism of how it happens and then putting a timescale to it. There are precedents in the recent past when sea level rose at 10 mm a year compared with the current 3.6mm a year. At 10mm a year or 100 mm every ten years or one meter in 100 years we could see some serious consequences with inundation of major cities and infrastructure but a sudden ice sheet collapse could bring this foreword in an irregular timescale.

Thanks Bob. The Big numbers in climate change are in the regions where nobody lives and these are the oceans and the poles. There is a lot going on and there are very few long term records to compare them with. This is s good video but it is long so get comfortable. https://www.youtube.com/watch?v=1ihnoSLmqT4

Reply

Bob Bristow

2/10/2014 09:26:32 am

Very interesting and educational - thanks for posting

Reply

jim adams

31/1/2015 10:24:32 am

(Hey \bob – this is version 2 .. i've replaced the 4th paragraph which seems to have disappeared in version 1. You can erase version 1 of this if you want.

Thanks Bob. I knew a lot of what you said, i learned a lot (and my appreciations and acknowledgments), plus, i have a couple additions:

On Greenland, ( NatGeo, 6/2010, Melt Zone ) shows good photos of an 85m gallon ice lake that opened a channel down and disappeared faster than the Niagara Falls could fall. In addition to the "rotting" of the ice you mention, liquid water at the bottom of a glacier is the best lubricant a glacier could have, increasing it's speed on it's way to the sea.

The ice sheets which floated away wouldn't have added any to sea level rise, but they did something more important .... they stopped being a plug that kept the glaciers moving --- well ... glacially. In West Antarctica at least, when the sea ice plugs floated away, the glaciers started moving seaward 8 to 10 times faster, Add soot on the summer surface so liquid water is cascading to the base of these glaciers and what is called "run away glacial melt" becomes possible.

My fear is this run away glacial melt will cause sea level rise to happen faster than the IPCCs current prediction (which is what you use) – to 4 to 6 feet or more by the end of this century. I wouldn't mind in the least being wrong, but i'm afraid i'm right and planners are only planning for a few inches of sea level rise and – they also say we don't have to prepare for the occasional big storms because they're rare and occasional and unpredictable.

I appreciate IPCC forecasts, but i notice that each installment of the IPCC documents makes global sea rise both faster and sooner, We've gone from a predicted 1 foot rise in a couple hundred years to a two foot rise in less than a century. And tho they mention that soot has an effect on increasing melt rates, they don't measure the rate of soot increase AND the increase in the rate of melt. They also don't talk about methane increasing -- not just from fracking but from the permafrost, and they didn't look at the fossil record which has records of the times the methane came out of the permafrost -- rapidly. They do say we should prepare for more bigger and stronger weather events.

In Peter Ward's: The Flooded Earth: Our Future In a World Without Ice Caps), he starts the book in Antarctica, up on the ice, wading thru slush which was almost boot top deep. Ward's a paleontologist, and in this book he explores his researches into the strata of other global warming events down thru deep time. He notes ours is happening faster than most and that therefore there is less time for adapting and resilience to help us out of our tough spots.

Here, i'm adding in a little book (just because) – William Ruddiman's Plows, Plagues, and Petroleum: How Humans Took Control of Climate – which has the best explanation of how we human's inadvertently changed the climate of our planet starting about 8k years ago – and we're just barely starting to understand the forces we've unleashed.

Reply

jim adams

31/1/2015 09:56:54 am

Thanks Bob. I knew a lot of what you said, i learned a lot, and i have a couple additions:

On Greenland, ( NatGeo, 6/2010, Melt Zone ) shows good photos of an 85m gallon ice lake that opened a channel down and disappeared faster than the Niagara Falls. In addition to the "rotting" of the ice you mention, liquid water at the bottom of a glacier is the best lubricant a glacier could have, increasing it's speed on it's way to the sea.

The ice sheets which floated away wouldn't have added any to sea level rise, but they did something more important .... they stopped being a plug that kept the glaciers moving --- well ... glacially. In West Antarctica at least, when the sea ice plugs floated away, the glaciers started moving seaward 8 to 10 times faster, Add soot on the summer surface so liquid water is cascading to the base of these glaciers and what is called "run away glacial melt" becomes possible.

I appreciate IPCC forecasts, but i notice that each installment of the IPCC documents makes global sea rise both faster and sooner, We've gone from a predicted 1 foot rise in a couple hundred years to a two foot rise in less than a century. And tho they mention that soot has an effect on increasing melt rates, they don't measure the rate of soot increase AND the increase in the rate of melt. They also don't talk about methane increasing -- not just from fracking but from the permafrost, and they didn't look at the fossil record which has records of the times the methane came out of the permafrost -- rapidly.

In Peter Ward's: The Flooded Earth: Our Future In a World Without Ice Caps), he starts the book in Antarctica, up on the ice, wading thru slush which was almost boot top deep. Ward's a paleontologist, and in this book he explores his researches into the strata of other global warming events down thru deep time. He notes ours is happening faster than most and that therefore there is less time for adapting and resilience to help us out of our tough spots.

Here, i'm adding in a little book (just because) – William Ruddiman's Plows, Plagues, and Petroleum: How Humans Took Control of Climate – which has the best explanation of how we human's inadvertently changed the climate of our planet starting about 8k years ago – and we're just barely starting to understand the forces we've unleashed